Hydrogen purification forPEM Fuel Cell drive systems. Recent progress and perspectives on the CO-PROX reaction

Carbon monoxide oxidation is one of the simplest catalytic reactions and, as such, has been extensively studied in catalysis research. It is receiving considerable research interest because of its importance in many applications, such as lowering CO emissions from automobiles and industries, including removing CO from hydrogen gas fuel. Hydrogen is used as a fuel for Polymer Electrolyte Membrane Fuel Cells (PEMFCs) and it can be produced through steam reforming or auto-thermal reforming of alcohols1 and hydrocarbons in combination with the water gas shift reaction. Nevertheless, PEMFC Pt anode catalysts are highly sensitive to the presence of even traces of CO and therefore methodologies have to be developed for decreasing the CO concentration in the hydrogen feed down to ppm levels, with a minimum H2 loss. Currently, Preferential Oxidation of CO (CO-PROX) is one of the most suitable and cost effective methods of purification of H2 because of its high CO conversion rate at low temperature range, which is preferable for PEMFCs operating conditions, with negligible H2 consumption. Noble metals, particularly platinum-based catalysts, have shown to be active and selective in the CO-PROX reaction2. However, due to high prices and the scarcity of noble metals, attention has been given mostly to non-noble metal or low noble metal catalysts3-7. Transition metals supported on suitable metal oxides are good substitute catalysts and, among them, copper-ceria based catalysts have attracted special interest due to their low cost and easy availability. Furthermore, they seem to be the best choice because results obtained by these catalysts are comparable and sometimes higher than those obtained by the conventional noble metal ones. This talk will address some aspects of the structure-reactivity relationship in several copper-ceria based systems for the CO-PROX reaction and recent advancements will be briefly reviewed.